1. Field of the Invention
The present invention relates to a backlight assembly, and more particularly, to a backlight assembly and liquid crystal display device having the same.
2. Discussion of the Related Art
There are various types of flat panel displays, for example, plasma display panels, field emission displays, light emitting diodes, liquid crystal displays, and the like.
Liquid crystal display devices display images by controlling the transmittance of light from an external source. Hence, LCDs are incapable of displaying images in the dark without a light source.
To solve this problem, backlight assemblies have been developed to provide a light source for the LCD when there is insufficient external light to display an image, for example, in a dark room. Generally, it is desirable for a backlight assembly to provide high luminance, high efficiency, luminance uniformity, long endurance, slimness, lightweight, low price, and the like.
Generally the lamps utilized in the backlight assembly are either cold cathode fluorescent lamps (CCFL) or external electrode fluorescent lamps (EEFL). Although the CCFL provides high luminance, its increased cost compared to the EEFL has resulted in increased research and development of EEFL backlight assemblies.
FIG. 1 is a layout of an EEFL backlight assembly of the related art, and FIG. 2 is a magnified perspective diagram of area-A of the backlight assembly in FIG. 1.
Referring to FIG. 1 and FIG. 2, the backlight assembly according to the related art includes: a plurality of external electrode fluorescent lamps (EEFLs) 1 each of which has a positive and negative electrode 2 and 3 positioned at opposite ends of each lamp; and common positive and negative electrode parts 4 and 5 having fitting portions 6 to allow the positive and negative electrodes 2 and 3 of the EEFLs 1 to be fitted therein. The fitting portions 6 are integral to the common positive and negative electrode parts 4 and 5, respectively, thereby electrically connecting the fitting portions 6 to the common positive and negative electrode parts 4 and 5.
As illustrated in FIG. 1, the distance between the common positive electrode part 4 and the negative electrode part 5 is equal to the length of an EEFL 1.
The positive and negative electrodes 2 and 3 of each of the EEFLs 1 are fitted in the fitting portions 6 provided on the common positive and negative electrode parts 4 and 5, respectively. Hence, the EEFLs 1 are connected parallel to the common positive and negative electrode parts 4 and 5.
When a high voltage is applied to the common positive and negative electrode parts 4 and 5, the voltage is supplied simultaneously to the respective positive and negative electrodes 2 and 3 of the EEFLs 1 via the fitting portions 6, thereby simultaneously producing light from each of the EEFLs 1.
The above-configured backlight assembly is suitable for a small-screen liquid crystal display panel. Since the small-screen liquid crystal display panel has a relatively small size, the number of EEFLs required in the backlight assembly is small. However, for a wide-screen liquid crystal display panel, the number of EEFLs increases in proportion to the corresponding screen size. As a result, the tube current flowing in each EEFL is reduced in proportion to the number of EEFLs such that the intensity of light may be lowered. To compensate for the reduced tube current, a higher voltage can be applied. Yet, in such a case, current consumption increases.
An EEFL having a U-type symmetric structure has been proposed to lower the number of EEFLs. A pair of the related art straight EEFLs, as illustrated in FIG. 1, can be replace by an U-type EEFL so that current consumption is reduced. Both end portions of the EEFL having the U-type symmetric structure are aligned on the same line.
However, as both of the end portions of a symmetric U-type EEFL are aligned on the same line to connect the U-type EEFL to the common positive and negative electrode parts, the common positive and negative electrode parts are situated on the same line, whereby a short circuit may occur.